As used herein, "ordered polymers" "extended-chain aromatic-heterocyclic ordered polymers," "thermotropic," and "lyotropic" liquid crystalline polymers, all refer to one or more of the known classes of polymers having a fixed molecular orientation in space i.e., linear, circular, star shaped, or the like.
This molecular orientation is believed to be imposed on the polymer structure by the nature of the monomer units making up the polymer. Many ordered polymers possess a linear "order" due to the linear nature of the monomeric repeating units comprising the polymeric chain. Linear ordered polymers are also known as "rod-like" polymers.
For example, U.S. Pat. No. 4,423,202 to Choe, discloses a process for the production of para-ordered, aromatic heterocyclic polymers having an average molecular weight in the range of from about 10,000 to 30,000.
U.S. Pat. No. 4,377,546 to Helminiak, discloses a process for the preparation of composite films prepared from para-ordered, rod-like, aromatic, heterocyclic polymers embedded in an amorphous heterocyclic system.
U.S. Pat. Nos. 4,323,493 and 4,321,357 to Keske et al., disclose melt prepared, ordered, linear, crystalline injection moldable polymers containing aliphatic, cycloaliphatic and araliphatic moieties.
U.S. Pat. No. 4,229,566 to Evers et al., describes para-ordered aromatic heterocyclic polymers characterized by the presence of diphenoxybenzene "swivel" sections in the polymer chain.
U.S. Pat. No. 4,207,407 to Helminiak et al. discloses composite films prepared from a para-ordered, rod-like aromatic heterocyclic polymer admixed with a flexible, coil-like amorphous heterocyclic polymer.
U.S. Pat. No. 4,108,835 to Arnold et al., describes para-ordered aromatic heterocyclic polymers containing pendant phenyl groups along the polymer chain backbone.
U.S. Pat. No. 4,051,108 to Helminiak et al., discloses a process for the preparation of films and coatings from para-ordered aromatic heterocyclic polymers.
Ordered polymer solutions in polyphosphoric acids (including PBzT compositions) useful as a dope in the production of polymeric fibers and films are described in U.S. Pat. Nos. 4,533,692, 4,533,693 and 4,533,724 (to Wolfe et al.).
The disclosures of each of the above described patents are incorporated herein by reference.
Film processing methods and apparatus have been available for a number of years. However, it is not believed that the methods previously utilized for standard polymeric films, can readily be employed in the formation of lyotropic or thermotropic polymer films, especially films having the unique characteristics of those prepared herein.
For example, U.S. Pat. No. 4,370,293 to Petersen-Hoj describes a method and apparatus for the manufacture of biaxially oriented plastic films, particularly polyester films. The process described for polyester comprises extruding polyester through an annular die to form a seamless tube and inflating the tube by means of a pressurized gas. The expanded tube thus formed is drawn out in a longitudinal direction, cooled and flattened. The flattened tube is heated to the orientation temperature of the film, expanded again, and stretched in its longitudinal direction. These stretching techniques are said to impart a biaxial orientation to the polymeric backbone of the film.
Similarly, U.S. Pat. No. 4,011,128 to Suzuki describes a method and apparatus for forming a cross-oriented film, wherein a non-oriented film to be treated is first formed by conventional methods, then cross-oriented by stretching and twisting. In addition the cross-oriented film is flattened so as to continuously form a laminated cross-oriented film.
U.S. Pat. No. 4,358,330 to Aronovici describes a method and apparatus for manufacturing films having pairs of adjacent layers whose molecular orientation is in different directions. The method employed is a modification of the conventional "blown film" technique such that the molecular chains forming the layers of film are oriented substantially immediately prior to their solidifying.
U.S. Pat. No. 4,496,413 to Sharps, Jr., describes a process and apparatus for the preparation of a blocked cross-plied polymer film which involves the extrusion of a polymer melt through a tubular rotary die. The rotation of a single member of the die is said to impart a molecular orientation to the polymer in a transverse direction during the extrusion. The film is blocked by expanding the film and then pressing opposing walls together to produce a composite film having at least two layers, each having a transverse molecular orientation opposing the other. The composite film is said to have a balanced cross-ply.
The disclosures of each of the above described patents are incorporated herein by reference.